Light emitting diodes (LEDs) are P/N diodes that emit light when voltages are applied across the P/N junctions. Traditional methods of fabricating LEDs consist of growing and patterning epitaxial layers of semiconductor materials on a wafer having a growth substrate, such as sapphire, using semiconductor manufacturing processes. After growing the epitaxial layers, the wafer is diced into dies and the dies are bonded to supporting structures, like lead-frames, for measurement of their optical and electrical properties. Measured LED dies are sorted, or binned, in accordance with their measured properties and those dies with the desired properties are packaged into LED chips.
While existing methods of fabricating LEDs have generally been adequate for their intended purposes, they have not been entirely satisfactory. For example, measurements of the diced LED dies, known as chip-level binning, incur extra manufacturing time and cost, and therefore is not suitable for mass production. In addition, the growth substrate of the LED dies, such as sapphire of a conventional LED or copper of a vertical LED, though suitable for growing the epitaxial layers, may have high thermal resistance. The high thermal resistance impairs the heat dissipation capability of the LED chips, degrading their performance and increasing the power. Accordingly, there is a need for LED fabrication methods that reduce manufacturing cost and increase performance of the LED chips.